Fluid and cellular samples collected from the buccal cavity contain a number of analytes or markers that are indicative of diseases or other health conditions of the sample donors. These samples, which include saliva and oral mucosal transudate (OMT), are referred to as oral fluid samples in this application. The analytes contained in the oral fluid samples include biomarkers, such as specific antibodies to, and antigens from, pathogens, chemical markers such as cocaine and other drug abuse markers, and genetic markers. Because of the noninvasive nature of collecting oral fluid samples, these samples are preferred, where appropriate, to use for the analyte detection.
One commonly used method for collecting an oral fluid sample is the use of a collection pad such as a sponge, which is connected to a handle. The collection pad absorbs the oral fluid while its surface can be used to collect epithelial cells by rubbing against the oral mucosa, including the surface of the gum. To collect an oral sample, one can rub the pad against the surface of gum and place the collection pad inside the buccal cavity. The collection pad now contains both epithelial cells and the saliva.
There are three general methods for recovering the sample from the collection pad. One method involves inserting the collection pad into an elution buffer and, after equilibration with the buffer, removing the collection pad. The second method involves wringing the collection pad by pressing the pad against a surface. For example, U.S. Pat. No. 5,339,829 describes a device which consists of a plunger attached with a collection pad and a syringe barrel, which is used to wring the saliva out of the pad. Yet another method for recovering the oral fluid sample from the collection pad is centrifugation.
There are a number of shortcomings for these methods of oral fluid sample recovery. While direct removal of the collection pad from a sample elution solution is simple, it considerably reduces the recovered sample amount as the collection pad itself can absorb a considerable amount of the sample when it is removed, leading to insufficient amounts of sample or a highly diluted sample for analyte detection. Wringing the sample out of the collection pad is difficult to perform and recovery efficiency is often inconsistent. Centrifugation involves the use of a centrifuge, which is not always available, particularly at point-of-care settings.
Similar problems exist for collecting other biological samples. These samples include, but are not limited to, vaginal specimens, wound specimens, and environmental samples.
We have now invented a simple device, which allows efficient extraction of the fluidic and adsorbed materials from the sample collection pad by simply pulling the collection pad through a narrow passage, resulting in the recovery of a considerable amount of the samples without using centrifugation. The method of collecting and recovering a sample described in the present invention is simple and user friendly.